Due to characteristic of a radio channel, when a digital mobile communication system transmits data, a bit error may occur by various types of causes. Therefore, a channel code that is used to correct the bit error is significantly important.
A turbo code and a low-density parity-check (LDPC) code are generally used as a channel code that approaches a Shannon capacity in an aspect of the configurable decoding complexity. The turbo code and the LDPC code are based on a turbo principle.
The turbo principle denotes iterative exchanging of soft-decision information between a plurality of modules. The turbo principle may iteratively update a log-likelihood ratio (LLR) value of a bit based on an extrinsic LLR value of a decoder. In a process of decoding a channel according to the turbo principle, as a number of iterative decodings increases, a convergence rate may also increase. Therefore, performance may be improved. However, when the number of iterative decodings increases, a calculation amount may also increase. In this case, there may be some problems in improving the performance.
Accordingly, there is a need for an apparatus that can improve iterative receiving performance, iterative decoding performance, and a convergence rate with using an existing turbo principle.